[Pacemaker] Shouldn't colocation -inf: be mandatory?

[Vadym Chepkov]

On Tue, Jun 15, 2010 at 9:14 AM, Andrew Beekhof <andrew at beekhof.net> wrote:
> On Tue, Jun 15, 2010 at 2:57 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
>>
>> On Jun 15, 2010, at 7:50 AM, Andrew Beekhof wrote:
>>
>>> On Tue, Jun 15, 2010 at 1:38 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
>>>>
>>>> On Jun 15, 2010, at 4:57 AM, Andrew Beekhof wrote:
>>>>
>>>>> On Tue, Jun 15, 2010 at 10:23 AM, Andreas Kurz <andreas.kurz at linbit.com> wrote:
>>>>>> On Tuesday 15 June 2010 08:40:58 Andrew Beekhof wrote:
>>>>>>> On Mon, Jun 14, 2010 at 4:22 PM, Vadym Chepkov <vchepkov at gmail.com> wrote:
>>>>>>>> On Jun 7, 2010, at 8:04 AM, Vadym Chepkov wrote:
>>>>>>>>> I filed bug 2435, glad to hear "it's not me"
>>>>>>>>
>>>>>>>> Andrew closed this bug
>>>>>>>> (http://developerbugs.linux-foundation.org/show_bug.cgi?id=2435) as
>>>>>>>> resolved, but I respectfully disagree.
>>>>>>>>
>>>>>>>> I will try to explain a problem again in this list.
>>>>>>>>
>>>>>>>> lets assume you want to have several resources running on the same node.
>>>>>>>> They are independent, so if one is going down, others shouldn't be
>>>>>>>> stopped. You would do this by using a resource set, like this:
>>>>>>>>
>>>>>>>> primitive dummy1 ocf:pacemaker:Dummy
>>>>>>>> primitive dummy2 ocf:pacemaker:Dummy
>>>>>>>> primitive dummy3 ocf:pacemaker:Dummy
>>>>>>>> colocation together inf: ( dummy1 dummy2 dummy3 )
>>>>>>>>
>>>>>>>> and I expect them to run on the same host, but they are not and I
>>>>>>>> attached hb_report to the case to prove it.
>>>>>>>>
>>>>>>>> Andrew closed it with the comment "Thats because you have
>>>>>>>> sequential="false" for the colocation set." But sequential="false" means
>>>>>>>> doesn't matter what order do they start.
>>>>>>>
>>>>>>> No.  Thats not what it means.
>>>>>>> And I believe I should know.
>>>>>>>
>>>>>>> It means that the members of the set are NOT collocated with each
>>>>>>> other, only with any preceding set.
>>>>>>
>>>>>> Just for clarification:
>>>>>>
>>>>>> colocation together inf: ( dummy1 dummy2 dummy3 ) dummy4
>>>>>>
>>>>>> .... is a shortcut for:
>>>>>>
>>>>>> colocation together1 inf: dummy4 dummy1
>>>>>> colocation together1 inf: dummy4 dummy2
>>>>>> colocation together1 inf: dummy4 dummy3
>>>>>>
>>>>>> ... is that correct?
>>>>>
>>>>> Only if sequential != false.
>>>>> For some reason the shell appears to be setting that by default.
>>>>>
>>>>>>
>>>>>> To pick up Vadym's Question:
>>>>>>
>>>>>> *  what would be the correct syntax to say "run-together-but-dont-care-if-one-
>>>>>> dies-or-is-not-runable"?
>>>>>
>>>>> Choose a score < inf, just like regular colocation constraints.
>>>>
>>>> Ah, ok, thanks, I guess in my mind anything less then inf was "advisory".
>>>
>>> They are.
>>>
>>> Advisory is the only way to deal with the
>>> "but-dont-care-if-one-dies-or-is-not-runable" part.
>>>
>>>> As long as I keep it above any resource-stickiness it should be in fact mandatory, right?
>>>> Or something else needs to be taken to consideration?
>>
>> what about this part? what do I need to do to prevent them from running on different nodes for sure?
>
> You can't have it both ways.
> Either they have to run on the same node or they can remain active
> when one or more die.
>
> Although you could do:
>
> d1 ( d2 d3 d4 )
>
> That would almost get what you want, unless d1 dies.

I guess I would have to keep the most significant as an anchor, I can
leave with it.
Unfortunately, as far as I understand, there is no way do define this
in shell config now, because shell adds sequential=false when it sees
().

>
>>
>>
>>>>
>>>> On a side note, I was trying to figure out how to make a set from two resources, so I just added a proper xml and checked what crm shell say about it. And it shows it like this:
>>>>
>>>> colocation together 5000: _rsc_set_ dummy1 dummy2
>>>
>>> Strange.  Dejan?
>>>
>>>>
>>>> Who knew? I didn't see it anywhere in documentation.
>>>>
>>>> Anyway, just so I get it right, what would be the opposite constraint (which is what this thread started from)
>>>> If I want to have same dummy1, dummy2, dummy3 resources, but I don't want any of them ever to run simultaneously on the same host. What wold be the proper anti-colocation constraint for this configuration?
>>>
>>> Score = -inf, plus the patch, plus sequential = true (or unset).
>>> Not sure how that looks in shell syntax though.
>>
>> My guess is for two resources it's
>> colocation onlyone -inf: _rsc_set_ dummy1 dummy2
>
> I certainly hope not.
>
>> and a patch. Would you include it in 1.0.9, by any chance?
>
> If it lands in the next few days.
>

That reminds me of an old joke.
The bus driver is looking at the girl running to the bus stop and
thinking: "Would she make it on time?"

:)

Vadym